Diaphragm Morphology Assessed by Computed Tomography in Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is associated with abnormal skeletal muscle morphology and function. To test the hypothesis that diaphragm muscle morphology assessed by computed tomography (CT) imaging would be associated with COPD severity, exacerbations, health status, and exercise capacity. The COPD Morphometry Study is a cross-sectional study that enrolled a clinical sample of smokers with COPD.

Dyspnea and surface inspiratory electromyograms in mechanically ventilated patients.

Context: Pressure support ventilation (PSV) must be tailored to the load capacity balance of the respiratory system. While "over assistance" generated hyperinflation and ineffective efforts, "under assistance" increased respiratory drive and causes dyspnea. Surface electromyograms (sEMGs) of extradiaphragmatic inspiratory muscles were responsive to respiratory loading/unloading.

Repetitive magnetic stimulation of the phrenic nerves for diaphragm conditioning: a normative study of feasibility and optimal settings.

Electrical stimulation can enhance muscle function. We applied repetitive cervical magnetic phrenic stimulation (rCMS) to induce diaphragm contractions in 7 healthy subjects (800 ms trains; transdiaphragmatic pressure (Pdi) measurements; tolerance ratings). Each rCMS train produced a sustained diaphragm contraction.

Mechanical ventilation-induced diaphragm disuse in humans triggers autophagy.

Rationale: Controlled mechanical ventilation (CMV) results in atrophy of the human diaphragm. The autophagy-lysosome pathway (ALP) contributes to skeletal muscle proteolysis, but its contribution to diaphragmatic protein degradation in mechanically ventilated patients is unknown.

Objectives: To evaluate the autophagy pathway responses to CMV in the diaphragm and limb muscles of humans and to identify the roles of FOXO transcription factors in these responses.

Neurally adjusted ventilatory assist increases respiratory variability and complexity in acute respiratory failure.

Background: Neurally adjusted ventilatory assist (NAVA) is a partial ventilatory support mode where positive pressure is provided in relation to diaphragmatic electrical activity (EAdi). Central inspiratory activity is normally not monotonous, but it demonstrates short-term variability and complexity. The authors reasoned that NAVA should produce a more "natural" or variable breathing pattern than other modes.

Effects of inspiratory loading on the chaotic dynamics of ventilatory flow in humans.

Human ventilation at rest exhibits complexity and chaos. The aim of this study was to determine whether suprapontine interferences with the automatic breathing control could contribute to ventilatory chaos. We conducted a post hoc analysis of a previous study performed in awake volunteers exhibiting cortical pre-motor potentials during inspiratory loading.

Contribution to structural intensity tool: application to the cancellation of ECG interference in diaphragmatic EMG.

This paper is concerned with the problem of localizing the typical features of a signal when it is observed with noise in order to align a set of curves. Structural intensity (SI) is a recent tool that computes the "density" of the location of the modulus maxima of a wavelet representation along various scales in order to identify singularities of an unknown signal. As a contribution to this novel approach we establish a modified SI using the Berkner transform which allows maxima linkage to insure accurate localization of singularities.

Tracheal pressure regulated volume assist ventilation in acute respiratory failure.

Purpose: Proportional assist ventilation (PAV) uses volume assist (VAV) and flow assist ventilation (FAV) to reduce elastic and resistive effort, respectively. Proportional assist ventilation may be difficult to apply clinically, particularly due to FAV related considerations. It was hypothesized that regulating tracheal (Ptr) rather than airway opening pressure (Pao), to overcome endotracheal tube related resistive effort, during VAV would provide an effective alternative method of ventilation.

Incidence, risk factors and consequences of ICU delirium.

Objective: Delirium in the critically ill is reported in 11-80% of patients. We estimated the incidence of delirium using a validated scale in a large cohort of ICU patients and determined the associated risk factors and outcomes.

Design And Setting: Prospective study in a 16-bed medical-surgical intensive care unit (ICU).

Olanzapine vs haloperidol: treating delirium in a critical care setting.

Objective: To compare the safety and estimate the response profile of olanzapine, a second-generation antipsychotic, to haloperidol in the treatment of delirium in the critical care setting.

Design: Prospective randomized trial.

Setting: Tertiary care university affiliated critical care unit.

Controlled mechanical ventilation leads to remodeling of the rat diaphragm.

Little is known about the structural response of the diaphragm to controlled mechanical ventilation. We examined effects of this intervention on muscle mass, myosin heavy chain isoforms, and contractile function in the rat diaphragm. Animals were mechanically ventilated for up to 4 days, and comparisons were made with normal control rats as well as spontaneously breathing animals anesthetized for the same duration as the mechanical ventilation group.

Mechanical ventilation protects against diaphragm injury in sepsis: interaction of oxidative and mechanical stresses.

Overproduction of nitric oxide (NO) with attendant oxidative and nitrosative stress has been implicated in sepsis-induced diaphragm dysfunction. Here we determined the impact of controlled mechanical ventilation (MV) on rat diaphragm sarcolemmal injury, inducible NO synthase (iNOS) expression, and oxidative stress during endotoxemia. At 4 h after injection of endotoxin, impaired sarcolemmal integrity and decreased force production by the diaphragm were observed in spontaneously breathing rats.